Adjustable contour knife



Jan. 17, 1961 w. J. PRATT 2,968,057

ADJUSTABLE CONTOUR KNIF E Filed Nov. 13, 1958 INVENTOR.

WILLIAM J. PRATT ADJUSTABLE CONTOUR KNIFE William J. Pratt, NorthBellmore, N.Y., assignor of one-half to James P. Malone, Mineola, NY.

' Filed Nov. 13, 1958, Ser. No. 773,758

1 Claim. (Cl. 15-236) This invention relates to means for spreadingplastic material smoothly over a curved surface, and more particularlyto a flexible knife spreader having an adjustable curvature.

Spreader knives such as putty knives are used for spreading andsmoothing plastic materials over a work surface. Spreaders which utilizethe knife edge for smoothing are called knives and those which use theflat portion are called trowels. The common putty knife is not suitablefor working on curved surfaces since it has a straight edge. Typicalcurved surfaces are the body surfaces of automobiles. Dents and holes inthese surfaces are generally repaired by applying a quick hardeningplastic and smoothing, sanding, and painting. Commercially availableplastics are used which when mixed with a solvent can be applied andthen harden quickly in about 4 or 5 minutes so that it may be filed orsanded at the end of that time. It is, therefore, important that theplastic material be quickly and accurately applied while the material isstill workable. Straight edge knives such as putty knives are not tooadaptable for curved surfaces since many strokes have to be made and theresult is still a series of straight surfaces rather than a curve.

The present invention solves this difiiculty by providing a spreaderknife having a screw adjustment clamp connected to its sides which isadapted to impart a curvature to the knife which will match the curvedsurface being worked. The present invention provides a flat flexiblemember, for instance, of steel having a first straight end,

a smaller end, and two tapering sides connecting the ends.

The smaller end may be provided with a plastic or rubber holding stripso that it may be conveniently held in the hand without contacting anyedge of the blade. An adjustable clamp is connected to each side of theflexible member near the holding end and the clamp is provided with awing nut so that a proper curvature may be given to the knife. Theclamping screw is mounted close to the surface of the member so as toprovide the minimum obstruction. The. present invention may be called acontour knife as it is adapted to match the contour of the surface beingworked.

Accordingly, a principal object of the invention is to provide a new andimproved spreader knife.

Another object of the invention is to provide a new and improvedspreader knife having an adjustable curvature.

Another object of the invention is to provide a new and improved contourknife.

Another object of the invention is to provide a new and improvedadjustable curvature contour knife.

Another object of the invention is to provide a new and improvedspreader knife comprising a flat flexible member and adjustable clampingmeans connecting the sides thereof and operable to impart adjustablecurvature to match the contour of the surface being worked.

These and other objects of the invention will become 2,968,057 PatentedJan. 17,- 1961 apparent from the following specification and drawings,of which;

Figure 1 is a perspective view of an embodiment of the invention.

Figure 2 is a sectional view along the line 2-2 of Figure 1, and

Figure 3 is a diagram illustrative of the operation of the invention.

Referring to the figures the invention comprises a flat flexible member1 which is preferably of a good grade of steel. It has a straight edge 2at one end, the other end 3 being smaller and preferably curved toprovide a convenient hand hold. The sides 4 and 5 of the member 1 aresmoothly tapering except that they may have notches 4' and 5 toaccommodate the adjustable clamping member.

The adjustable clamping member comprises a threaded stud or bolt 10having a wing nut 11 connected at one end and a notched hook portion 12at the other end. The stud 10 is connected to the member 1 by means of atubular ferrule 14 having notch 14' and the notch in hook 12 adapted tofit the side edges of the flexible member.

The clamping means is assembled by passing the bolt 10 through thenotched ferrule, mounting the notches in book and ferrule against theside edges of the member 1 and then tightening the bolts in the nut 12so as to impart a curvature to the member 1 as illustrated by the curvededge 2 of Figure 2. The curvature is along an axis perpendicular to thebolt 10. The member 1 is preferably made of a good grade of steel sothat it has a spring action which securely holds the clamping member inplace. Other means of mounting the clamping member may be provided, forinstance, by welding or otherwise connecting one or more ferrules ontothe member 1 or by cutting the member 1 in a pattern having mountingears for accommodating the clamp. However, applicant has found that thepresent method of mounting the notched ferrule and hook is adequate andeliminates the possibility of breaking the welded connections or themounted ears. A washer 15 is preferably placed between the ferrule 14and the wing nut 11. Figure 3 shows the use one typical curved surfaceof an automobile fender 20.

The contour knife preferably has a cylindrical rubber or plastic lip 16mounted on the holding end to facilitate holding in the hand. The knifeis held by placing the curved end 3 in the palm of the hand with thethumb on one side and the other four fingers on the other side. Thethumb may be braced against the clamp bolt 10 if desired. The clampingmeans does not provide a perfect curve along the full extent of the edge2 as the outer sides tend to flatten off. However, the whole area isgenerally not used and, if necessary, a larger size knife may be usedfor a larger size curved surface.

The flexible member of the present invention may be adjusted to aninfinite variety of curves going from a completely flat surface to ahorseshoe shaped surface. For the high degrees of curvature the ferruletype mounting shown is preferable to a mounting welded or otherwisefixed to the knife since the member 1 may move within the notches of theferrules without straining any fixed connections such as weldedconnections.

The ferrule type mounting has been chosen since it holds the bolt asclose as possible to the surface and there are no projecting knobs tolimit the angle at which the knife is held to the work surface.

The present type mounting of the adjustment means also permits reversingthe mounting means to the other side of the member 1 in order tostraighten it out if the member 1 should take a permanent set.

The present invention may also be used for cutting 3 i knives for makingcurved cuts in materials such as sheet rubber. In this embodiment theedge 2 of the spreader would be sharpened to provide a cutting edge.

The present invention has been illustrated in connection with auto bodyrepair work but is not limited to such use and may be used Wherever itis desired tos rn ooth a plastic material along a curved surface. Forinstance, it could be used in plastering curved walls, repairing statuesor other objects having curved surfaces.

I claim:

A contour knife comprising a flat flexible member having a firststraight end, a second smaller end, and two tapering sides connectingsaid ends, means to curve said References Cited in the file of thispatent UNITED STATES PATENTS 1,167,797 Clawson Jan. 11, 1916 1,264,350Unsinger Apr. 30, 1918 2,756,499 Liesunaitis July 31, 1956

